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Re: [Xen-devel] accumulate_guest_flags no longer exists in xen 3.4.3

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject: Re: [Xen-devel] accumulate_guest_flags no longer exists in xen 3.4.3
From: "K.C. Lee" <kcl.joseph@xxxxxxxxx>
Date: Wed, 29 Sep 2010 15:08:11 +0800
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On Mon, Sep 27, 2010 at 5:51 PM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
At 04:35 +0100 on 27 Sep (1285562121), K.C. Lee wrote:
> Hi,
> I found that accumulate_guest_flags(struct vcpu *v, walk_t *gw) defined in xen 3.1.0 could not be found in xen 3.4.3.
> Also, I found that guest_walk_tables(struct vcpu *v, unsigned long va, walk_t *gw, ...) in xen 3.4.3 contanis code block: "guest_l1e_get_flags(gw->eff_l1e) ^ _PAGE_NX_BIT" which can only be found in accumulate_guest_flags. Besides, I also found a comment in "We will accumulate, in rc, the set of flags that are missing".
> I want to know if accumulate_guest_flags integrated into guest_walk_tables in the version of xen 3.4.3?

Yes.  The HAP code had introduced its own pagetable-walking routines
which were missing some logic; they were merged with the original
shadow-code pagetable walker.

> And if so, how can I use guest_walk_tables instead of accumulate_guest_flags to get the same return value and walk_t *gw?

What exactly are you trying to do?  For most purposes the function you
need is paging_gva_to_gfn(), which will find and walk the guest's
pagetables for you, and figure out the pagefault error code if you need
to inject a pagefault.

Dear Tim,

I'm a beginner of xen.

I'm trying to figure out what xen does when a page fault happened so I trace sh_page_fault() and then have many questions about what these functions do and how can I use them.

Would you please show me what paging_gva_to_gfn(), guest_walk_tables() and accumulate_guest_flags() do?

Is there any references to these functions?

Thank you very much.





> Any suggestion is appreciated.
> Thank you very much.

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Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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